1. Field of the Invention
The present invention relates to fuel blending processes and apparatus, and more particularly, to a fuel blending process and apparatus for obtaining a fuel mixture which will not freeze or form solid particles, e.g., wax particles, above a predetermined temperature.
2. Description of the Prior Art
During the winter months in northern states, diesel fuel is normally cut back by adding kerosine or No. 1 fuel oil, kerosine or No. 1 heating oil to No. 2 fuel oil or heating oil to reduce problems, such as plugged fuel filters, supply lines and screens, associated with wax crystallization from the diesel fuel blend at low temperatures. In general, an assumed fluidity point or cloud point provides the basis for winter blending as the predictor of low temperature operability limits of diesel equipment. In other words, the temperature at which wax crystals or other solid materials from in the diesel fuel is attempted to be determined in order to ascertain the percentage of No. 1 fuel which must be added to meet the diesel fuel fluidity control temperatures during colder months. In general, as used herein, fluidity refers to fuel in a liquid state without interfering solid or semi-solid, e.g., viscous, particles. Heretofore, diesel fuel blending processes have been based on assumed, arbitrary assumptions regarding the fluidity levels of the No. 2 heating oil component of the ultimate diesel fuel mixture. This occurs when, e.g., a diesel fuel retail distributor buys No. 2 fuel oil from many different suppliers and refineries which supply No. 2 heating oil having differing fluidity levels. For winter blending purposes, the distributor assumes a threshold fluidity level high enough so that all suppliers will supply only product which a freezer or forms solid wax particles below or at this level. While some product will be at this level, most will be below it, the latter resulting in wastage of No. 1 fuel.
Although the actual fluidity level is known at the refinery, this information becomes lost during distribution, thus necessitating the above-described assumed threshold fluidity value. At the refinery level, the actual fluidity value is obtained by a procedure based on the ASTM D-2386 Freeze Point Method or ASTM D-2500 Cloud Pont Method or ASTM D-3117 Wax Appearance Point Method, each of which is a laboratory method for determining the point at which wax crystals in the diesel fuel melt or appear. Determination of freeze point, cloud point or wax appearance point at the refinery level requires cumbersome equipment and a trained technician who must constantly monitor the fuel sample to ascertain visually when melting or wax crystal formation occurs. Thus, these methods are highly subjective and yield non-standard results. Additonally, the cumbersome equipment makes them inconvenient for field use.
Using the conventional methods, during winter months 10-60% kerosine/No. 1 fuel oil is typically blended with No. 2 fuel oil to meet diesel fuel fluidity requirements. The percentage of No. 1 fuel (kerosine) added is dictated by monthly winter blending guidelines specific for each terminal and is based on historical weather data and an assumed fluidity level, as described above, of the base No. 2 fuel oil. The use of an inexact, assumed No. 2 fuel fluidity point frequently leads to overblending in some instances, resulting in No. 1 fuel wastage, and underblending in others, resulting in fuel line, filter and screen clogging.
No fuel blending process or apparatus has heretofore provided on-site precise, tailored diesel fuel blending for optimizing the blend ratio of the component fuels forming the ultimate fuel mixture in order to obtain a fuel mixture which will not freeze or form solid particles above a predetermined temperature.
Accordingly, it is an object of the present invention to provide a tailored diesel fuel blending process and apparatus to fulfill the above-described needs heretofore unmet by prior art systems.
It is also an object of the present invention to provide a tailored, diesel fuel blending process and apparatus whereby reliance on assumed fluidity levels of a No. 2 fuel oil component can be avoided by an on-site actual determination of the fluidity level of the No. 2 fuel oil component.
It is also an object of the present invention to provide an opto-electrical, tailored, diesel fuel blending process and apparatus whereby substantial savings of required No. 1 fuel oil can be obtained, and whereby more No. 1 fuel oil can be made available for upgrading to, e.g., jet fuel.
It is yet another object of the present invention to provide an electro-optical, tailored, diesel fuel blending process and apparatus whereby a high density diesel fuel blend with higher BTU content and better fuel economy is provided.
It is a further object of the present invention to provide a reliable automatic, opto-electrical, tailored fuel blending process and apparatus.